In an automotive vehicle, it is common practice to locate a fuel pump within a fuel tank. The fuel pump comprises a direct current electric motor having carbon brushes that contact a commutator and are connected to positive and negative terminals of an external power supply. The electric motor is contained with a housing that includes a metallic shell in contact with the fuel.
It has been proposed to utilize an automotive fuel that contains a high concentration of ethanol up to about 85%. During operation, the ethanol tends to become ionized. The ions may react with electrical components within the electric motor of the fuel pump. In particular, positive ions derived from the ethanol may react with metallic agents added to the negative carbon brush to form a resistive film that inhibits current flow between the brush and commutator, thereby reducing the operational life of the motor.
Therefore, there is a need for a fuel pump that inhibits reaction between components of the electric motor, particularly a negative carbon brush, and ions within the fuel and so extends the useful life of an electric fuel pump, particularly when used with high alcohol fuel.